Efficient characterization of RF sources for the design of noise suppression filters

The filter development process, to reduce occurring conducted emissions, is still an unsolved problem within EMC considerations, due to the filter attenuation depends on the impedance values of the device under test. The paper presents a method how to characterize arbitrary active applications within the frequency domain. The evaluated noise sources are described as Y or Z- matrices with additional active sources in respect to Theveninpsilas law. Through a translation from the time into the frequency domain even circuits including non-linear elements can be considered. The method is presented for the example of a power stage circuit and it is considered how to translate the technique into measurements.